POLYMORPHIC RESTRICTION PATTERNS OF RIBOSOMAL INTERNAL TRANSCRIBED SPACERS IN THE BIOCONTROL FUNGUS PUCCINIA-CARDUORUM CORRELATE WITH WEED HOST ORIGIN

The internal transcribed spacer (ITS) regions of ribosomal DNA were am plified by PCR and used to develop genetic markers for isolates of Puc cinia carduorum being evaluated for biological control of Carduus thoe rmeri (musk thistle). Unique patterns were produced upon restriction o f ITS DNA amplified from four separate Puccinia spp. Restriction patte rns of ITS DNA of isolates of P. carduorum from Carduus acanthoides an d C. thoermeri were distinct from those of P. carduorum from Carduus t enuiflorus and Carduus pycnocephalus. By this technique, isolates of P . carduorum from four different weed hosts can be differentiated from other Puccinia spp. and separated into two host groups.